Contribution of plum and cherry rootstocks to virus incidence in New Zealand stone fruit trees

Abstract

Rootstocks used in the past for stone fruit trees in New Zealand were traced, where possible, back to their time of importation. Some of the rootstocks had been in use in New Zealand since before the turn of this century, but the most important were imported mainly from England between 1930 and 1960. Rootstocks used commonly for plums (Prunus salicina Lindl.), apricots (P. armenica L.), and sweet cherries (P. avium L.), and also some which were trialled but did not become popular, were tested for the presence of virus diseases. With plums, the four most important rootstocks ('Brompton’, ‘Marianna’, ‘Myrobalan B’, and ‘St Julien A') were free from infection. However, Prunus necrotic ringspot, dark green sunken mottle (apple chlorotic leaf spot), and plum line pattern viruses occurred in others. In cherries, Prunus necrotic ringspot virus occurred in most of the rootstocks, with prune dwarf, green ring mottle, and little cherry viruses sometimes also being present. ‘Kentish Red’, a P. cerasus (L.) cherry rootstock, had the highest incidence of infection. Presence of the viruses in the plum and cherry rootstocks would have contributed to the high incidence of infection in plum, apricot, and cherry trees, and explained why peaches (P. persica L.) and nectarines (P. persica var. nucipersica (Borkh.) C. K. Schneider), which are normally grown on peach seedling rootstocks were generally less commonly infected.

Key words:

• Prunus
• plum rootstocks
• cherry rootstocks
• virus disease
• disease testing